The crash does not appear to be the result of hostile fire, Staff Sgt. Ryan Whitney of the 1st Special Operations Wing said Monday. “But that won’t be completely determined until there is a thorough investigation.”

Whitney said there is no way to know at this point how long an investigation will take.

According to Whitney, Hall was a U-28A pilot on his seventh deployment. He was commissioned through ROTC at The Citadel in 2004. He had been assigned to the 319th SOS since 2007 and had 1,300 combat flight hours.

Whitlock was also a U-28A pilot, Whitney said. He was commissioned in 2006 through the Officer Training School. Whitlock had been with the 319th since 2008 and had logged 800 combat flight hours.

Wilkens, a combat systems operator assigned to the 34th Special Operations Squadron, was on his third deployment. He joined the Air Force in 2009 after graduating from the Air Force Academy. He had 400 combat hours.

Scholten was a missions system operator assigned to the 25th Intelligence Squadron. He enlisted in 2007 and had more than 900 combat hours, Whitney said. This was his third deployment.

The airmen were the only people aboard the aircraft when it crashed at about 8 p.m. local time during a routine flight, according to a statement from U.S. Africa Command. More details on what caused the accident were not immediately available.